Artificial nose is so sensitive it can detect cancers in your breath

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The nose is an amazing organ. It can smell around corners, through walls, and in pitch darkness. It can look back in time to detect traces of objects that are not even present any more. It can distinguish between many thousands of different aromatic molecules and their various combinations, allowing us to associate our strongest memories with smells, rather than sights or sounds. The mechanics of how exactly it does this are still being worked out in all their detail, but a new “artificial nose” for detecting and identifying airborne compounds may still be about to surpass it nonetheless.

Unlike the mammalian nose, which works using specialized signalling neurons with an affinity for different compounds, this artificial nose works with mechanical cantilevers as its primary mechanism. The researchers coated the cantilevers with layers of various synthetic substances tailored to their molecule of interest. This means the artificial nose, sensitive though it may be, is far less versatile than your own sniffer; this one must be built to detect a particular substance in the air.

Once that definition has been built into the nose, however, the system seems exquisitely well tuned for detection. Each of their tiny detection units is just 2.5 μm thick and 500 μm across, and maintains a tiny electric circuit with a detectable level of resistance. When the molecule of interest touches this device it distorts the shape of the specially tailored coating, which in turn deforms the system and changes resistance over the whole. By detecting these changes in resistance, the team was able to detect incredibly small concentrations of their target compound.

The system can target a wide variety of different molecules, it seems, including markers for disease. In this study recently presented at the International Conference on Micro Electrical Mechanical Systems, the researchers were able to reliably distinguish four cancer-stricken patients from four healthy ones, in a double-blind test. By keying on some of the same molecules used as markers for targeting anti-cancer drugs, this study looks to make diagnosis of such diseases much faster, cheaper, and less invasive.

The bloodhound’s nose is still unmatched in terms of sensitivity and versatility.

However, the implications for accurate smelling technology are numerous. Prospective drug-sniffing dogs might want to look into alternate career paths, but this technology could threaten most inspection workers. Drugs and other active substances are more appropriate for detection by this technology, explosives like C4 could be found quite easily as well. The only restriction would be having to maintain a separate nose for every molecule you want to detect — but with further research a multi-compound detector tuned to all the most common drug compounds is very easy to imagine.

Smell occupies some particularly ancient real-estate in the brain, and probably relies on neurology much more primitive than do our eyes or ears. That’s because identifying trace elements in a larger chemical milieu is so important for so many reasons — whether you’re sniffing food before popping it in your mouth or approving it for the supermarket shelf, the task is essentially the same. Sifting the air around an object is incredibly easy, and could speed safety and quality checks across the board — and destroy a lot of jobs in that sector as well. In automated security, criminals can fool cameras, or muffle their movements to avoid microphones, but absolutely nobody can completely get rid of their smell.

A sufficiently advanced nose, with the ability to collect and cross-reference many different chemical markers, could even identify people this way. Each person does have a distinctive smell, and that could be used for extremely quick biological identification. This is not so different from the idea of using the distinct characteristics of our gut bacterial population for the same purpose — but this signature would be airborne and around us at all times. It could allow passive identification schemes that put the mall in Minority Report to shame.